In conventional stamping, embossing, or die cutting presses, it has long been the practice to provide an apertured chase for mounting the stamping, embossing or die cutting dies on a flat bed press or the apertured chase of a rotary press. Fasteners received in the apertures of the flat bed chase or cylinder chase of a rotary press engage the edge of the die to hold the dies in selected positions on the flat bed or rotary press.
Typical flat bed chases are 22 in. by 28 in., 28 in. by 40 in. or 39 in. by 50 in. in size. These chases are usually from about 0.625 in. to about 2 in. thick steel with closely spaced apertures formed in the chase for receiving fasteners such as toggle devices. Similarly, rotary cylinders for mounting of curved dies generally are in the 8 in. to 12 in. diameter range and have an apertured sleeve chase for the rotary press cylinder, in which the sleeve chase has closely spaced fastener receiving holes. Fasteners are employed to secure a multiplicity of stamping, embossing, or die cutting dies to the die mounting surface of the apertured chases. Each fastener, which is preferably a toggle device, is introduced into an aperture in the flat bed chase or the apertured sleeve chase for the cylinder of a rotary press adjacent to an edge of a respective die and the toggle device expanded with a tool to bring a beveled edge of the hold down device into engagement with a complementally beveled edge of a respective die. Typically as many as six fasteners may be required to secure a rectangular stamping, embossing, or die cutting die to a flat bed press chase or rotary press chase. Chases of the type described typically cost many thousands of dollars. The toggle hold down devices are also relatively expensive and in a typical die set up, there may be a need for as many as 100 fasteners, depending upon the size of the flat bed chase or the diameter of the rotary cylinder chase and the number of dies attached to the flat bed or rotary press.
Set up, also known as lock-up, of foil stamping, embossing, or die cutting dies on an apertured chase, whether flat or cylindrical, is very time consuming. Each of the dies must be oriented on a respective apertured chase in disposition such that the design image of each die correctly and precisely aligns with image design artwork.
Lock-up is accomplished by placing the first of a series of foil stamping, embossing, or die cutting dies on the die support surface of the apertured chase of a flat bed press, or the apertured sleeve for the cylinder of a rotary press in approximately the position where the die image will align with design image artwork. Fasteners in the nature of conventional toggle devices are inserted in the nearest aperture of the flat bed chase or rotary press chase in a position such that an inclined surface of each toggle device is against the inclined edge of the die plate. A certain degree of movement of the die with respect to the chase or cylinder may be accomplished by adjusting the toggle device contained within a particular aperture in the multi-apertured chase.
After the first die plate has been secured to the chase in proper disposition, the entire securement process must be repeated with the next die plate and continued until all of the die plates have been attached to the chase. Manifestly, this is a very expensive procedure from the standpoint of personnel costs, and in certain instances excessive downtime of the press. The lock-up must be carried out in accordance with a successive time consuming step-by-step process of attaching a multiplicity of flat or curved die plates to an apertured chase. In addition, once all of the dies are mounted on its chase, whether it be flat or cylindrical, adjustment of individual stamping, embossing or die cutting may be required to bring respective die images into exact alignment with design image artwork.
Because of the high labor costs involved in lock-up of multiple die stamping, embossing or die cutting dies on flat bed or rotary presses, some press operators elect to dedicate a specific flat or cylindrical chase with dies mounted thereon to a high volume processing operation. The result is that the operator must acquire and keep on hand a number of individual chases with dies in place thereon for a particular job. In view of the high cost of chases and the costs involved in providing a large number of toggle hold down devices for the dies, locked up dedicated flat or cylindrical chases is an expensive but often necessary undertaking.
Cylindrical die supporting plates have been provided for rotary press cylinders, with a plurality of curved dies being attached to the surface of the cylindrical support plate. In order to mount the cylindrical die support plate on the press cylinder, it has been necessary to remove a side plate from the press, which can take as long as four hours and is an expensive, cumbersome, and time-consuming operation. In addition, because of the time involved in make ready of a cylindrical die supporting plate assembly, many press operators have elected to provide a separate cylinder and associated dies for each job, with the pre-madeup cylinders being interchanged as necessary. The costs incurred limited this practice to very large runs in order to fully amortize the labor and equipment expenses.
Alternatively, curved dies have been fabricated and used in the past on rotary press cylinders, but the curved dies were limited to a circumferential arc no greater than 180°, so that the dies could be attached to the surface of the cylinder. This requirement limited the applicability of such arrangement for rotary presses. Given the limitation of a die no greater than 180° in circumference, press operators have mounted a series of individual curved die plates on the press cylinder, which did extend more than 180° around the circumference of the cylinder. The dies had to be individually mounted on the cylinder of the press oriented such that each was in register with respective images on the substrate brought into contact with the dies. This was recognized to be so labor intensive and time-consuming that low volume runs were of limited practicality.